Instruments and techniques for controlled removal of epidermal layers

ABSTRACT

An instrument and technique for the removal of epidermal layers in a controlled manner utilizing a hand-held instrument with a working end that (i) a vacuum aspiration system, (ii) a source for delivery of a sterile fluids or pharmacological agents to the skin; and (iii) a skin interface surface in the working end that has specially shape structure for abrading surface layers of the patient&#39;s epidermis as the working end is moved over the patient&#39;s skin while at the same time causing rapid penetration of the fluids into the skin for therapeutic purposes. Movement of the working end across the skin causes abrasion of the surface layers in a path over the patient&#39;s skin. The method of the invention may be used in a periodic treatment for the removal of superficial skin layers that enhances the synthesis of dermal collagen aggregates by inducing the body&#39;s natural wound healing response. The method of the invention creates more normal dermal architectures in skin with limited depths of skin removal by the series of superficial treatments that may be comparable to the extent of neocollagenesis caused by a deep skin removal treatment (e.g., CO 2  laser skin removal).

PRIORITY INFORMATION

This application is a continuation of U.S. patent application Ser. No.10/699,747, filed Nov. 3, 2003, which is a continuation of U.S. patentapplication Ser. No. 09/648,025 filed Aug. 25, 2000, now U.S. Pat. No.6,641,591, which claims the priority benefit under 35 U.S.C. §119(e) ofProvisional U.S. Patent Application Ser. No. 60/150,782, filed Aug. 26,1999, the entire contents of these applications being herebyincorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to devices for dermatology and moreparticularly to a hand-held instrument with a working end that carries(i) a negative pressure aspiration system, (ii) a source for delivery ofa sterile fluids to the skin; and (iii) a skin interface surface in theworking end that has specially shape structure for abrading surfacelayers of the patient's epidermis as the working end is moved over thepatient's skin while at the same time causing rapid penetration of thefluids into the skin for therapeutic purposes.

2. Description of the Related Art

Dermatologists and plastic surgeons have used various methods forremoving superficial skin layers to cause the growth of new skin layers(i.e., commonly described as skin resurfacing techniques) since theearly 1900's. Early skin resurfacing treatments used an acid such asphenol to etch away surface layers of a patient's skin that containeddamage to thereafter be replaced by new skin. (The term damage whenreferring to a skin disorder is herein defined as any cutaneous defect,e.g., including but not limited to rhytides, hyperpigmentation, acnescars, solar elastosis, other dyschromias, stria distensae, seborrheicdermatitus).

Following the removal of surface skin layers at a particular depth, nomatter the method of skin removal, the body's natural wound-healingresponse begins to regenerate the epidermis and underlying wounded skinlayers. The new skin layer will then cytologically and architecturallyresemble a younger and more normal skin. The range of resurfacingtreatments can be divided generally into three categories based on thedepth of the skin removal and wound: (i) superficial exfoliations orpeels extending into the epidermis, (ii) medium-depth resurfacingtreatments extending into the papillary dermis, and (iii) deepresurfacing treatments that remove tissue to the depth of the reticulardermis (see FIGS. 1A-1B).

Modem techniques for skin layer removal include: CO.sub.2 laserresurfacing which falls into the category of a deep resurfacingtreatment; Erbium laser resurfacing which generally is considered amedium-depth treatment; mechanical dermabrasion using high-speedabrasive wheels which results in a medium-depth or deep resurfacingtreatment; and chemical peels which may range from a superficial to adeep resurfacing treatment, depending on the treatment parameters. Arecent treatment, generally called micro-dermabrasion, has beendeveloped that uses an air-pressure source to deliver abrasive particlesdirectly against a patient's skin at high-velocities to abrade away skinlayers. Such a micro-dermabrasion modality may be likened tosandblasting albeit at velocities that do no cause excess pain anddiscomfort to the patient. Micro-dermabrasion as currently practicedfalls into the category of a superficial resurfacing treatment.

A superficial exfoliation, peel or abrasion removes some or all of theepidermis (see FIGS. 1A-1B) and thus is suited for treating very lightrhytides. Such a superficial exfoliation is not effective in treatingmany forms of damage to skin. A medium-depth resurfacing treatment thatextends into the papillary dermis (see FIG. 1B) can treat many types ofdamage to skin. Deep resurfacing treatments, such as CO.sub.2 lasertreatments, that extend well into the reticular dermis (see FIG. 1B)causes the most significant growth of new skin layers but carry the riskof scarring unless carefully controlled.

It is useful to briefly explain the body's mechanism of actuallyresurfacing skin in response to the removal of a significant depth ofdermal layers. Each of the above-listed depths of treatment disrupts theepidermal barrier, or a deeper dermal barrier (papillary or reticular),which initiates varied levels of the body's wound-healing response. Asuperficial skin layer removal typically causes a limited wound-healingresponse, including a transient inflammatory response and limitedcollagen synthesis within the dermis. In a medium-depth or a deeptreatment, the initial inflammatory stage leads to hemostasis through anactivated coagulation cascade. Chemotactic factors and fibrin lysisproducts cause neutrophils and monocytes to appear at the site of thewound. The neutrophils sterilize the wound site and the monocytesconvert to macrophages and elaborate growth factors which initiate thenext phase of the body's wound-healing response involving granulartissue formation. In this phase, fibroblasts generate a newextracellular matrix, particularly in the papillary and reticuilardermis, which is sustained by angiogenesis and protected anteriorly bythe reforming epithelial layer. The new extracellular matrix is largelycomposed of collagen fibers (particularly Types I and H) which are laiddown in compact parallel arrays (see FIG. 1B). It is largely thecollagen fibers that provide the structural integrity of the newskin—and contribute to the appearance of youthful skin.

All of the prevalent types of skin damage (rhytides, solar elastosiseffects, hyperpigmentation, acne scars, dyschromias, melasma, striadistensae) manifest common histologic and ultrastructuralcharacteristics, which in particular include disorganized and thinnercollagen aggregates, abnormalities in elastic fibers, and abnormalfibroblasts, melanocytes and keratinocytes that disrupt the normalarchitecture of the dermal layers. It is well recognized that there willbe a clinical improvement in the condition and appearance of a patient'sskin when a more normal architecture is regenerated by the body'swound-healing response. Of most significance to a clinical improvementis skin is the creation of more dense parallel collagen aggregates withdecreased periodicity (spacing between fibrils). The body'swound-healing response is responsible for synthesis of these collagenaggregates. In addition to the body's natural wound healing response,adjunct pharmaceutical treatments that are administered concurrent with,or following, a skin exfoliations can enhance the development ofcollagen aggregates to provide a more normal dermal architecture in theskin—the result being a more youthful appearing skin.

The deeper skin resurfacing treatments, such as laser ablation, chemicalpeels and mechanical dermabrasion have drawbacks. The treatments arebest used for treatments of a patient's face and may not be suited fortreating other portions of a patient's body. For example, laserresurfacing of a patient's neck or decolletage may result inpost-treatment pigmentation disorders. All the deep resurfacingtreatments are expensive, require anesthetics, and must be performed ina clinical setting. Perhaps, the most significant disadvantage to deepresurfacing treatments relates to the post-treatment recovery period. Itmay require up to several weeks or even months to fully recover and toallow the skin the form a new epidermal layer. During a period rangingfrom a few weeks to several weeks after a deep resurfacing treatment,the patient typically must wear heavy make-up to cover redness thusmaking the treatment acceptable only to women.

The superficial treatment offered by micro-dermabrasion has theadvantages of being performed without anesthetics and requiring noextended post-treatment recovery period. However, micro-dermabrasion ascurrently practices also has several disadvantages. First, amicro-dermabrasion treatment is adapted only for a superficialexfoliation of a patient's epidermis which does not treat many forms ofdamage to skin. Further, the current micro-dermabrasion devices causeabrasive effects in a focused area of the skin that is very small, forexample a few mm.sup.2, since all current devices use a single pin-holeorifice that jets air and abrasives to strike the skin in a highlyfocused area. Such a focused treatment area is suitable for superficialexfoliations when the working end of the device is passed over the skinin overlapping paths. Further, such focused energy delivery is not wellsuited for deeper skin removal where repeated passes may be necessary.Still further, current micro-dermabrasion devices are not suited fordeeper skin removal due to the pain associated with deep abrasions.Other disadvantages of the current micro-dermabrasion devices relate tothe aluminum oxide abrasive particles that are typically used. Aluminumoxide can contaminate the working environment and create a health hazardfor operators and patients alike. Inhalation of aluminum oxide particlesover time can result in serious respiratory disorders.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B are sectional illustrations of a patient's skin showingdermal layers.

FIG. 2 is a view of a Type “A” body and working end of the instrument ofthe invention.

FIG. 3 is an enlarged view of the working end of the instrument of FIG.2.

FIG. 4 is a sectional view of working end of FIG. 3.

FIG. 5 is a view showing the manner of using the working end of theinvention of FIGS. 3-4 in performing a method of the invention.

FIG. 6 is a view of a Type “B” body, working end and handle in anexploded view.

FIG. 7 is a view of the working end of the instrument of FIG. 6 and ahousing.

FIG. 8 is an enlarged view of the skin interface of the working end ofFIG. 7.

FIG. 9 is a sectional view of the skin interface of FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

1. Type “A” Skin Resurfacing System. Referring to FIGS. 2-3, anexemplary instrument system 5 is shown for removing superficial skinlayers. The instrument system 5 includes: (i) a hand-held body 18 with aworking end 20 that defines a skin interface surface portion indicatedat 25 in FIGS. 2-3. An opening portion 26 transitions into an interiorpassageway 28 that extends through the body to communicate with anegative (−) pressure source (or aspiration source) indicated at 30 thatoperates as vacuum means for aspirating skin debris from a targeted skinsurface treatment site TS.

Of particular interest, FIGS. 3-4 show views of the working end 20 withthe skin interface 25 being configured with a particular irregular orridged surface structure indicated at 32. The ridged surface structure32 further has a particular minimum width dimension W to accommodatefrom the ridge shape with as many as about 25 ridges on each side ofopening 26 depending on the overall dimensions of the working end 20.More particular aspects of the irregular or ridged surface structure 32will be described below.

In this preferred embodiment, the working end 20 is of any suitablematerial, such as a transparent medical grade plastic. The transparencyof the working end will assist the operator in localizing treatment in aparticular targeted skin treatment area. The overall transversedimension of the working end 20 of FIGS. 2-3 may be from around about5.0 mm. to about 50.0 mm. with a larger dimensioned end being adaptedfor treating a larger skin area (e.g., arms, back legs and decolletage).A typical dimension is from about 5.0 mm. to 15.0 mm. for a skintreatment site area TS around a patient's face.

The invention allows the area (e.g., in mm²) of opening 26 be in anyselected shape but preferably is an elongate shape in the center of theworking end 25. The open distal end 26 comprises the distal terminationof passageway 28 and the proximal end of the passageway in handle 18 isconnected to a flexible aspiration tube 33 that extends to a remotecollection reservoir 35 intermediate to the actual aspiration source 30.The aspiration source 30 thus is adapted to draw the working end 20 andmore particularly the skin interface 25 against the skin treatment siteTS to perform the method of the invention as will be described below.The aspiration source or negative (−) pressurization source 30 may beany suitable vacuum source known in the art. Between the aspirationsource 30 and remote collection reservoir 35 may be a filter 38subsystem that is known in the art for collecting aspirated skindetritus and spent crystalline agents CA that are captured in the opendistal end of passageway chamber 28. The collection reservoir 35 andfilter 38 are preferably of inexpensive plastic and other materials thatare disposable.

The aspiration source 30 may be provided with an adjustable valve means40 for adjusting the pressure level setting to any suitable range. Thephysician will learn from experience how to balance the pressure levelto attain the desired level of suction against the patient's skin. Atrigger or switch component 42 is provided as a foot-switch (FIG. 2) butany suitable finger switch in the body 18 also may be used.

The working end 20 also carries means for introducing abrasive crystalsinto the working end or distalmost end of passageway 28 to allowindividual loose crystalline agents CA to thereafter be captured betweenthe skin interface 25 and the patient's skin. In this embodiment, twochannels 44 a-44 b are provided together with flexible tubes 46 a-46 bto introduce the loose crystalline agents CA into the working end (seeFIGS. 2-4). Each distal portion 47 (collectively) of the channels 44a-44 b may comprise a small dimension aperture to limit the rate of flowof crystalline agents CA into the working end. The number of suchchannels (i.e., 44 a-44 n) may range from one to about ten and fallwithin the scope of the invention. Any singular or plural number ofchannels can serve the purpose of slowly introducing crystal into theworking end. Referring to FIGS. 2-3, the crystalline agent CA deliverysource 50 comprises a reservoir 55 that holds a suitable volume ofabrasive crystals for a single treatment or a number of treatments. Aflexible supply tube 56 extends between a remote the reservoir 55, andin this embodiment the tube is split to connect to the two channels 44a-44 b. Preferably, the remote reservoir 55 that carries the crystallineagent CA is unpressurized but carries air intake relief valve 58 suchthat any slight negative pressure created by the aspiration source 30when the skin interface is in contact with a patient's skin will drawcrystals to the working end. It should be appreciated that reservoir 55may be built into handle body 18 and fall within the scope of theinvention. The crystal delivery source 50 may carry crystals ranging insize from about 1 μm to about 50 μm in maximum cross-sectionaldimension, (for example, aluminum oxide crystals). Preferably, thecrystals are from about 5 μm to about 30 μm in maximum cross-sectionaldimension to allow a very fine abrasion of the epidermis.

It has been found that by a slight negative pressure environment theopen end 26 and passageway 28, the crystalline agent will be caused todribble into, or be sucked into, the passageway 28 in the working end20. Thereafter, the movement of the working end 20 in a sidewaysmovement over the skin causes a portion of the crystalline agent CAvolume to be captured temporarily in the irregular or corrugated surfacestructure of the skin interface 25. In this process of moving the skininterface 25 over the targeted treatment site TS, it has been found thatthe sharp-edged crystalline agents are rolled over and over while beingpressed into the surface of the skin and thereby abrade and remove theskin surface in a controllably gentle manner that is below any thresholdof significant pain.

After the spent crystals are rolled over and over by the skin interfacewhen moving in a first lateral direction across the skin, and after theworking end is then is reversed in directional movement across the skin,a portion of the spent crystals and abraded skin debris necessarily rollinto the central opening portion 26 wherein the negative pressureenvironment captures and aspirates the abraded materials to the remotecollection reservoir 35.

To facilitate the process described above, the invention is providedwith novel aspects that relate to the irregular or ridged surfacestructure 32 mentioned above. The entire skin interface 25 may be of anysuitable plan form (e.g., round, oval, rectangular etc.) and fall withinthe scope of the invention. More in particular, the interface 25 definesa 1^(st) outer periphery 25A and a 2^(nd) inner periphery 25B thatgenerally are in apposition to one another and are spaced apart by widthW with the inner periphery about the edge of opening 26 (see FIG. 3).

In a preferred embodiment shown in FIGS. 3-4, the concept of 1^(st) and2^(nd) peripheries 25A and 25B in apposition thus comprise peripheriesthat are dual and side-by-side as shown in FIG. 4 and are thus adaptedfor side-to-side lateral or sideways movement while performing thetechnique of the invention, for example which is a natural movement of ahuman hand over a patient's skin. Thus, the direction of the ridges 60extend generally transverse relative to a line drawn that indicates thedirection of movement of the working end 20 in performing the method ofthe invention. That is, in the exemplary working end of FIG. 4, theworking end is generally optimized for side-to-side or lateral movement.Thus, the ridge alignment is generally transverse to the direction ofmovement in operations indicated by arrow A. (In a circular working endthat is adapted generally for movement is any direction, the directionof the ridges 60 may be generally transverse to any direction ofmovement by being concentric relative to a central opening 26 (notshown)).

The terms irregular or ridged shape structure 32 as used herein meanthat a series of at least one projecting edge portion 62 a projectsdistally as a ridge within the skin interface portion 25. The irregularshape structure 32 further typically carries recessed portions or valleyportions 62 b that are recessed in the proximal direction intermediateto any plurality of projecting edge portions 62 a. These surfaceconfigurations for convenience are herein termed the primary shapestructure (or ridge and valley elements). The width of the skininterface 25 containing shape structure 32 may be from about 2.0 mm. to25.0 mm. or more and preferably is from about 3.0 mm. to 10.0 mm. Thenumber of ridges preferably are from about 1 ridge to 25 ridges on eachside of the opening 26. The height H of any ridge from the apex of theprojecting portion 62 a to the depth of the valley portion 62 b may befrom about 0.25 mm. to about 5.0 mm. and is preferably from about 0.5mm. to about 2.0 m. It has been found that various ridge heightdimensions are optimal depending on the patient's skin type. Further,but optionally, it has been found that secondary shape structure ofnotches or recessed grooves 66 configured across the primary shapestructure of ridge and valley elements may help introduce loose crystalsto regions of the skin interface 25 in contact with the skin which isdesirable. Such secondary grooves 66 are shown in FIG. 4 and arepreferably somewhat in alignment with an axis of channels 44 a-44 b thatintroduce crystals into the working end 20 thus allowing the crystals tobe suctioned into the valleys 62 b of the primary shape structure.

While the series of primary ridge and valley elements together thesecondary grooves seems to be optimal for the method described below, itshould be appreciated that the method also may be performed with a skininterface that has (i) only primary ridge and valley elements; (ii) oronly a particular surface roughness that is appropriate for partiallycapturing loose crystals as will be described below-as long as the skininterface has a minimum width of about 3.0 mm. which was described as apreferred width dimension previously.

FIG. 4 further shows that at least some of the crests or apexes of someof the ridge portions 62 a together with the outermost periphery of theskin interface 25 define an overall tissue-receiving shape 64 that mayrange from flat to concave and is shown in a preferred concaveconfiguration. The alternative shapes 64 a-44 b are intended to indicatean approximate range of shapes that are suitable. The apexes of ridges62 a need not all be at the same height to define shape 64. The purposeof the concave shape is to cause the outer periphery of the working endto be in firm contact with the tissue surface while the negativepressure from aspiration source 30 draws the skin into firm contact withtissue interface 25.

2. Practice of the Method of the Invention. Now turning to FIG. 5, asectional view of working end 20 shows the technique of the presentinvention in exfoliating or removing skin surface layers. FIG. 5 showsthe working end 20 after actuation of the negative (−) pressure source30 with the skin surface 70 initially being drawn into the concave shape64. The operating negative pressures may be in any suitable range thatis determined by investigation. It has been found by experimentationthat optimal pressure levels vary greatly depending on (i) the type ofskin targeted for treatment, (ii) the dimensions across the working end,and (iii) the dimensions of opening 26.

Next, the operator moves the skin interface 25 across a treatment siteTS which is a path on the patient's skin while still actuating moves thetrigger 42 thereby maintaining the negative pressure environment in thepassageway 26. The negative pressure environment within the working endcauses crystalline particles and entrained in air to be drawn intopassageway 28 proximate to the skin surface and into the shape structure32 of the skin interface 25. The sideways or lateral movement of theskin interface 25 captures a portion of the crystals between theinterface and the skin surface, in part by over-rolling them. Thecontinued rolling of the sharp-edged crystals trapped between theinstrument and the skin surface 70 causes an abrasion and removal of theskin surface in a controllable manner.

As working end is moved in a reverse direction, the negative pressureenvironment in the passageway 28 captures and aspirates the spentcrystals and skin debris to the remote collection reservoir 35. At theend of a particular lateral movement of the working end, the operatormay release the trigger 42 which terminates the crystal agent deliveryand further allows the operator to easily lift the working end from thepatient's skin. The treated path can be easily seen and the operatorthen can exfoliate another slightly overlapping or adjacent path byrepeating the above steps until surface removal is completed over thetargeted treatment area.

3. Type “B” Skin Resurfacing System. Referring to FIGS. 6-9, anotherexemplary instrument system and treatment device 205 is shown forremoving superficial skin layers. This system differs greatly from theType “A” embodiment in the mechanism of action that abrades the skinsince the Type “B” system uses a fluid media plus an abrading structureon the skin interface. Still several features of the Type “B” embodimentare similar to the Type “A” embodiment and the two modalities oftreatment may be used to complement one another.

FIG. 6 shows that a hand-held instrument 208 has a removable working end220 that defines a skin interface surface portion indicated at 225.Handle portion 227 a mates with housing 227 b. A flexible tube 228extends to a vacuum source 230. A fluid reservoir 235 carrying a fluidskin treatment media is housed in the handle although it could also be aremote reservoir.

Referring now to FIGS. 7-9, a first aperture arrangement consisting ofat least one port or opening portion 240 of skin interface 225 thatcommunicates with an interior passageway 242 that extends throughhousing 227 b to hose 228 and the vacuum or negative (−) pressuresource.

FIGS. 7-9 further show a second aperture arrangement in the skininterface consisting of at least one port or openings 250 that extendaround an outer periphery of the skin interface 225. These opening(s) ofthe second aperture arrangement are in fluid communication with thereservoir 235 and the treatment media therein. The skin interface has aseries of primary ridge elements 255 a and valley elements 255 btogether the secondary notches or grooves 260 as defined above withsimilar dimensional parameters. This embodiment differs however in thatthe apexes of ridge elements 255 a are substantially a sharp edge as arethe edged of the notches 260. Thus, these primary surface elements 255 aand secondary surface elements thereby define teeth therebetween thatseem well suited to abrading skin layers particularly after beinghydrated by the fluid source of the system. Experimentation has shownthat the vacuum source and fluid source may be reversed between thefirst and second aperture arrangements 240 and 250 with the method ofskin removal still working well. The vacuum system aspirates away skindebris and spent fluids as described previously. Of particular interest,the method of the invention appears to work well because the suction onthe skin treatment site very quickly hydrated, or puffs up, the skinwhich in turn make the surface layer susceptible to painless abrasion.The ability of the system to rapidly deliver fluids to subsurfacetissues allows the use of any pharmacological agent known in the art forenhancing skin rejuvenation as a part of the skin treatment. The systemcan use sterile water or saline solution for a treatment to removedermal tissue with the abrasive surface of the treatment device. Thesystem can also use a fluid carrying a chemical agent of a suitableconcentration be selected from a group of acids including TCA(trichloroacetic acid), a glycolic acid including an alphahydroxy acid(AHA), a lactic acid, a citric acid, or phenol as disclosed inco-pending U.S. patent application Ser. No. 09/524,731 (Docket No.19773-400510US) filed Mar. 14, 2000 which is incorporated herein by thisreference.

Specific features of the invention may be shown in some figures and notin others, and this is for convenience only and any feature may becombined with another in accordance with the invention. While theprinciples of the invention have been made clear in the exemplaryembodiments, it will be obvious to those skilled in the art thatmodifications of the structure, arrangement, proportions, elements, andmaterials may be utilized in the practice of the invention, andotherwise, which are particularly adapted to specific environments andoperative requirements without departing from the principles of theinvention. The appended claims are intended to cover and embrace any andall such modifications, with the limits only of the true purview, spiritand scope of the invention.

1. A method for abrading skin of a patient, comprising: (a) placing aworking end of a skin treatment device against the skin of the patient;(b) drawing the skin against a skin interface on the working end of theskin treatment device by applying suction to the skin through anaspiration opening in the working end; (c) moving the treatment deviceacross the skin; (d) abrading the skin drawn against the skin interface;and (e) removing skin debris through the aspiration opening in theworking end of the skin treatment device.
 2. The method of claim 1,further comprising providing a fluid to the skin.
 3. The method of claim2, wherein the fluid is provided with a crystalline abrasive.
 4. Themethod of claim 2, wherein the fluid hydrates the skin.
 5. The method ofclaim 2, wherein the fluid is provided with a pharmacologically-activeagent for treating skin.
 6. The method of claim 2, wherein the fluid isprovided with an agent selected from the class consisting of citric acidand lactic acid.
 7. The method of claim 2, wherein the fluid is providedwith an agent selected from the class comprising TCA (trichloroaceticacid), glycolic acid, alphahydroxy acid (AHA).
 8. The method of claim 3,wherein providing a fluid to the skin the fluid further comprisesproviding through a fluid opening provided in the working end of theskin treatment device.
 9. A hand-held device for treating the skinsurface of a patient, comprising: a body comprising a working end thatincludes a skin interface and a passageway extending through the body toan aspiration opening formed in the skin interface; and means forabrading the skin surface of the patient with the skin interface andremoving skin debris from the skin surface through the aspirationopening..
 10. The system of claim 9, further comprising means forsupplying a fluid to the skin surface.